Abstract
The -Nearest Neighbors (NN) query is an important spatial query in mobile sensor networks. In this work we extend kNN to include a distance constraint, calling it a -distant -nearest-neighbors (-NN) query, which finds the sensor nodes nearest to a query point that are also at or greater distance from each other. The query results indicate the objects nearest to the area of interest that are scattered from each other by at least distance l. The -NN query can be used in most NN applications for the case of well distributed query results. To process an -NN query, we must discover all sets of NN sensor nodes and then find all pairs of sensor nodes in each set that are separated by at least a distance . Given the limited battery and computing power of sensor nodes, this -NN query processing is problematically expensive in terms of energy consumption. In this paper, we propose a greedy approach for -NN query processing in mobile sensor networks. The key idea of the proposed approach is to divide the search space into subspaces whose all sides are . By selecting sensor nodes from the other subspaces near the query point, we guarantee accurate query results for -NN. In our experiments, we show that the proposed method exhibits superior performance compared with a post-processing based method using the NN query in terms of energy efficiency, query latency, and accuracy.
Highlights
Advancements in wireless technology and sensors have enabled rapid development of mobile sensor networks in which moving sensor nodes are wirelessly connected
Considering the limited computing power and batteries of sensor nodes, processing a - NN query is problematically expensive in terms of energy consumption in mobile sensor networks
We propose a greedy approach for - NN query processing in mobile sensor networks
Summary
Advancements in wireless technology and sensors have enabled rapid development of mobile sensor networks in which moving sensor nodes are wirelessly connected. Collecting a massive amount of sensed data to a centralized database incurs unnecessary and redundant message transmissions These traditional techniques are infeasible for mobile sensor networks due to the high communication cost and energy consumption. Studies of these methods have shown improved performance by using index and ad hoc geographic routing techniques They have focused on reducing the number of transmissions because the greatest energy consumption by sensor nodes is due to communication. Considering the limited computing power and batteries of sensor nodes, processing a - NN query is problematically expensive in terms of energy consumption in mobile sensor networks. We propose a greedy approach for - NN query processing in mobile sensor networks. By selecting sensor nodes from the other subspaces near the query point, we can obtain accurate query results for - NN.
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